The Obama administration's plan to force new reporting requirements on thousands of gun dealers near the Mexico border is under fire from members of his own party.

At least three Democrats in the Senate and several more in the House are voicing opposition to a proposed regulation from the Bureau of Alcohol, Tobacco, Firearms and Explosives that would require about 8,500 gun dealers in four states – California, New Mexico, Arizona and Texas – to report gun sales of two or more high-powered rifles sold within five consecutive business days.

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The proposal isn't connected in any way to the mass shooting in Arizona last weekend that left six people dead and 14 others wounded, including Rep. Gabrielle Giffords, D-Ariz., because the suspect used a handgun, which is already covered under these reporting requirements.

The new regulation would cover semiautomatic rifles greater than .22 caliber with detachable magazines.

Sen. Mark Begich, D-Alaska, has asked the ATF to withdraw its request to the White House for emergency authority to enact the regulation.

"While I understand the importance of cracking down on violence and gun trafficking along the U.S.-Mexico border, this wide-reaching regulation would punish law-abiding American gun owners and impede their Second Amendment rights," Begich wrote in a letter last week to ATF Acting Director Kenneth Melson. "Instead, we must secure our border and target Mexican drug cartels, as well as participating offenders in the United States."

The proposal also faces opposition from Montana's two Democratic senators, Max Baucus and Jon Tester, as well as 36 House members in both parties who say the regulation would subject gun dealers to burdensome requirements.

They want the administration to enforce the agency's existing power to ensure gun dealers are in compliance with the law.

In a letter to President Obama last month, House members, including Reps. Dan Boren, D-Okla, Nick Rahall, D-W. Va., Mike Ross, D-Ark., Denny Rehberg, R-Mont., and Ron Paul, R-Texas,said the regulation should be reviewed by Congress first.

"While Congress has authorized multiple sales reporting for handguns, we have never extended this authority to other types of firearms," they wrote. "Expanding this power by executive decree would be an end run around Congress."

Other Republicans who have expressed opposition are Arizona Sens. John McCain and Jon Kyle.

The White House did not respond to an e-mail seeking comment.

The controversy over the proposal comes as the Tucson shooting renews debate on gun control laws and Obama struggles to get Senate confirmation for his choice to run the ATF, Andrew Traver. The agency has not had a director for more than four years.

Obama resubmitted the nomination last week after it died in the last session of Congress. But Traver still faces fierce opposition from groups such as the National Rifle Association.

"Traver has been deeply aligned with gun control advocates and anti-gun activities," the NRA said in a statement last week. "This makes him the wrong choice to lead an enforcement agency that has almost exclusive oversight and control over the firearms industry, its retailers and consumers."

The ATF announced the new proposed regulation last month. The agency was expecting approval from the Office of Management and Budget last week but the White House is still reviewing the request.

"Review of this ATF information is proceeding expeditiously," an OMB spokeswoman said in an e-mail to FoxNews.com.

The ATF has rejected the notion that its regulation will violate Second Amendment rights or impose burdensome paperwork on gun dealers.

"These reports will give ATF real-time leads for the investigation of gun trafficking," Melson said in a webcast last month announcing the proposal.

"ATF's experience in these source states proves that multiple purchases of the described rifles are strong indicators of firearms trafficking to Mexico," he said. "By obtaining information about these multiple sales, ATF increase the likelihood of uncovering and disrupting trafficking schemes before the firearms make their way into Mexico."

Melson called the gun dealers who would be affected by the regulation "good citizens who share ATF's interest and commitment in keeping guns out of criminal hands."

"Working together, we can do that without infringing on the rights of law abiding citizens," he said.

Mexico's drug war has claimed more than 30,000 lives since President Felipe Calderon launched a crackdown on the powerful drug cartels shortly after assuming control in late 2006. ATF tracks the weapons found in Mexico and has linked tens of thousands of recovered guns to U.S. dealers.

Scott Thomasson, the chief spokesman for ATF, told FoxNews.com that the agency is pushing for this new regulation now because since 2004, there's been a 100 percent increase by Mexican drug cartels using rifles, which are not covered by any reporting requirements.

"This move by the ATF to capture this information is a direct result in the cartel shift in weapon of choice and in our attempt to stem the flow of violence," he said.

"We seem to be losing sight of the fact that this simple requirement, and it is a simple requirement, is one of the greatest tools we have as investigators in stopping and stemming violence before it happens and identifying those who put guns in the hands of people who shouldn't have them," he said.

"It makes sense that law enforcement should be alerted if someone is buying five, 10 or 100 assault weapons, when it's likely that those guns could be headed to drug cartels in Mexico," said Paul Helmke, president of the Brady Campaign.

"It will give ATF the same amount of information about people who buy military-style assault weapons in bulk that they already have had for more than 40 years about people who buy handguns in bulk," he said in a statement. "It's the kind of crime-fighting information that our law enforcement officials ought to have if we want to reduce the number of assault weapons being trafficked illegally to Mexico, as well as to American cities."

The NRA, which says it is keeping a close eye on the ATF, has vowed to make every effort possible to block the proposal.

"ATF doesn't have the authority to unilaterally impose this new requirement," the group said on its website. "If the Obama administration is going to run roughshod over the statutory limitations of the ATF in this regard, what other restrictions on their authority will they attempt to undermine or ignore?"